/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isBalanced(TreeNode root) {
        if(root==null){
            return true;
        }
        return Math.abs(depth(root.left)-depth(root.right))<=1&&isBalanced(root.left)&&  isBalanced  (root.right);

    }
    public int depth(TreeNode root){
        if(root==null){
            return 0;
        }
        return Math.max(depth(root.left),depth(root.right))+1;
    }
}
